1. Field of the Invention
This invention relates to inhalation therapy devices, and more particularly, to the design and construction of a nebulizer which has a variable flow rate control.
2. Prior Art
It has been determined that a number of respiratory ailments can be treated by the inhalation of finely divided particles of water or other liquid medicaments. However, in the case of some ailments, the particles must travel into the lower respiratory tract. In other ailments, application of the particles to the upper respiratory tract is preferred. In either situation, it is also desirable to be able to regulate the rate at which the liquid medicament is supplied per unit time. This is generally referred to as the "nebulization rate". By regulating both the nebulization rate and the particle size, accurate treatment of a wide range of respiratory diseases can be achieved.
The prior art is well aware of using of finely divided liquid particles in the treatment of respiratory ailments, and a number of prior art nebulizer devices have evolved. In general, these type of devices are shown in U.S. Pat. Nos. 2,882,026; 3,874,379; and 4,007,238. These nebulizers introduce a stream of gas into a chamber which entrains liquid particles. The liquid particles in the gas stream are then directed to the patient. Such devices contain a number of shortcomings. For example, they are constructed such that for a given flow rate of gas (LPM) into the chamber, liquid particles of a specific size are produced. In addition, the number of particles entrained by the gas per unit time is also fixed for any given flow rate of gas. If one were to change the flow rate of gas through these prior art devices, it is believed that not only would the amount of liquid particles entrained by the gas be changed, but the size of the liquid particles would also be changed. Thus, merely changing the flow rate of gas may prevent the particles from being directed either to the upper or lower respiratory tract.
U.S. Pat. No. 2,882,026 does disclose the use of a rotatable nozzle to produce ultra small liquid particles. This nozzle is mounted on a tube which is secured in place by means of a sleeve nut. However, such device requires that the nozzle be fixed in one position prior to operation of the device. In addition, such limited movement is not believed to be sufficient to achieve the necessary regulation of both the particle size and nebulization rate.